London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

Rail passengers on one of the UK’s busiest commuter routes faced major disruption today as rail chiefs introduced speed restrictions due to hot tracks.

A speed limit of 20 mph was put in place at lunchtime on routes into and out of Waterloo as the ageing track struggled to cope with surface temperatures approaching 50C.

Network Rail blamed antiquated wooden “bearers” used on the line which are less able to adapt than the more modern concrete foundations when rising temperatures causes the track to expand, and even buckle.

Trains have to be slowed as a safety precaution, particularly when they cross points, at a short stretch of track between Clapham Junction and Nine Elms/Battersea on the approach to Waterloo. Other London rail routes were unaffected.

South West trains said it was cancelling some Waterloo services while others would not stop at stations along the route. Trains from Shepperton, Alton, Basingstoke and Vauxhall would be “thinned out” to maintain the punctuality of remaining services.

With the heatwave set to continue, Network Rail said the safe temperature threshold may be repeatedly breached and warned passengers they face disruption for much of the week.

Tory MP Mark Pritchard was on a train hit by delays out of Waterloo. He said: “Everybody on the train was either laughing or scornful. There is nothing cool about Network Rail bosses’ undeserved bonuses — and clearly nothing cool about their railway tracks.”

Anthony Smith, chief executive of the independent watchdog Passenger Focus, said: “Passengers’ whole day can be disrupted by a delay on the train so it is critical to get them good-quality information in plenty of time to help them plan alternative travel.”

A spokeswoman for South West Trains said: “We carry out a significant amount of work to prepare for the impact of hot weather by using hydraulic machines to artificially stress the rails ... over the weekend we have seen temperatures on our tracks of almost 50C. The ageing condition of our infrastructure has meant that despite this preparation work, we have had to impose speed restrictions.”